Die set unit and method for can manufacture



Sept. 23, 1969 L. M. PATARINI ET AL 3,468,153

DIE SET UNIT AND METHOD FOR CAN MANUFACTURE Filed Nov. 20, 1967 l 5 I l l 72 32 //vv/vr0/?s.

LEO/V M PATAR/IV/ 8 ELMERM/WNTGOMEPY Lou/s A. MAJOR B WTWNEHH 3,468,153 DIE SET UNIT AND METHOD FOR CAN MANUFACTURE Leon M. Patarini, Chicago, Elmer M. Montgomery, Glen Ellyn, and Louis A. Major, Chicago, Ill., assignors to National Can Corporation, Chicago, 11]., a corporation of Delaware Filed Nov. 20, 1967, Ser. No. 684,244 Int. Cl. B21b 17/02, 25/00; B21d 51/00 US. Cl. 72370 6 Claims ABSTRACT OF THE DISCLOSURE An apparatus and method for necking in the upper and lower end portions of a cylindrical metal container so that the seam resulting from attaching an end to the can body is flush with the side walls of the can body. The apparatus comprises an outer die which has the necked-in contour desired in the finished can, and an inner or backup die which comprises a head element, and a skirt member connected thereto by a smooth head radius, wherein the skirt member has a continuous cylindrical extent at the upper portion thereof, and has the lower portion thereof divided into a plurality of segments, each separated from the other by a slot extending vertically toward the top of the skirt unit, and in which the entire skirt unit is backed up on the radially interior portions thereof, by a hard but resilient rubber ring member. The method comprises forming one or more neckedin portions on the can body by forcing the end of the can body into the die set. In a preferred construction, the skirt member is constructed separately from the head member, but is tightly attached thereto in position of use.

Although the described apparatus is useful for necking in the ends of can of all types, it is particularly useful when used with cans which have a side seam which is either interlocked or overlapped, thereby presenting a double metal thickness, at the side seam portion thereof, to the die set.

BACKGROUND OF THE INVENTION Field of the invention The field of the present invention is can manufacture, and more particularly a method of forming a reduced diameter neck portion on one or both ends of a can body by moving the ends of a can body longitudinally into the pair of cooperating dies in which one of the die members is rigid, and the other is rigid in one part thereof, but stiff but resilient in another part thereof. Specifically, the invention relates to forming a reduced diameter neck by forcing an unflanged end portion of a can body into the die and thereby cold working the metal to desired contour.

Description of the prior art For many years, a standard container in the beer and beverage industry was an ordinary beer can of so-called three-piece construction, that is, a can in which a body was formed by rolling a flat blank into a cylinder, interlocking the edges of the blank and soldering them together, and then attaching two ends to the cylinder by a double seaming operation. A can of this construction comprises a cylindrical body with two end or double seams of approximately A6 of an inch thickness extending radially outwardly from the body.

Recently, however, impact extruded or deep drawn metal cans, particularly aluminum cans, have become commercially practical, and these cans are constructed of only two pieces, that is, the body and bottom end are integrally formed, and the top member is separately formed and attached to the top end by a double seam.

States Patent 3,468,153 Patented Sept. 23, 1969 A can such as this has a larger outside diameter at the top than at the bottom, since the bottom part has no double seam whereas the top end does. Thus, when cans such as these are placed in a multi-pack carrier, such as a so-called six-pack carton which grips the upper double scam, the package, when viewed from the end, is slightly trapezoidal in shape. This is because the top of the package is four seam widths wider than the bottom, and the cans tend to be disposed at a slight angle from the vertical when the cans are placed with the top seams thereof abutting each other.

Accordingly, some beer and beverage cans may be manufactured with a reduced diameter neck portion surmounting the remainder of the body portion, so that when a double seam is formed, the upper edges of the seam are approximately parallel to or flush with the outer radial edges of the remainder of the can body. Forming this reduced diameter neck adds one operation to the normal can making process, but is not particularly complex when performed on one piece aluminum bodies.

Since beer and beverage cans are literally sold by the billions every year, and since packaging equipment for such cans is complex, high-speed machinery, it is desired to standardize sizes as much as possible, but aluminum cans of the type just described represent hybrid size in the industry, inasmuch as their top or double seam diameters are slightly less than those of ordinary cans.

Accordingly, beer and beverage producers desire cans which may be interchangeably used on their packing equipment, while still giving them the option of which style of can to purchase, since this results in a reduced dependence on one type of supplier and one type of material and stimulates price and quality competition which is considered economically healthful.

However, attempts to neck in the unflanged end portions of conventional can bodies, in order to standardize double seam widths without changing steel can making equipment, have resulted in the creation of unsightly flat spots along the radius joining the reduced diameter neck portion to the remainder of the can body, as well as cracking and similar structural failures. This condition is caused by multiple thicknesses of metal in this area, and the only method heretofore known for correcting the situation required constructing a die set which made allowance for this multiple thickness. However, this solution was completely unsatisfactory, since it required orientation of each body to its required location in the die, and orientation machinery is well known to be unduly complex, expensive, unreliable and far too slow for the high speed handling of cans which is an economic necessity.

Thus, there was no known prior art method for satisfactorily forming a reduced diameter neck portion on an unflanged can body which is rapid, economical, and which did not require the orientation of a can body to a particular location relative to the die.

SUMMARY OF THE INVENTION In view of the shortcomings of the prior art, there has been a need for such a die set which would be simple and economical.

Accordingly, an object of the invention is to provide a die set which does not require orientation of the side seam of a can relative thereto, and which will form a satisfactory reduced diameter neck portion in the can body.

Another object is to provide a die set having a rigid exterior die and an interior, complementary mating die having a rigid head area, and a skirt portion which is partially segmented and which is joined to the head, and backed up by a still but resilient rubber ring.

The present invention achieves these objects and other objects and advantages inherent therein by providing a die set including an outer die with a necked-in contour, and an inner die which includes a head element and a skirt member connected to the head element by a radius, and wherein the skirt member has a continuous cylindrical extent on the upper portion thereof, and has the lower portion thereof divided into a plurality of segments, each separated from the other by a cut or slot extending upwardly toward the head portion, and in which the entire skirt unit is backed up on the inside thereof by a hard but resilient rubber ring member. Providing such a die set makes it possible to perform the necking-in operating merely by forcing one or both ends of a can body into such a die set, without the necessity of orienting the body in relation to the die set, even where the can body contains an overlapped or interlocked side seam.

The manner in which these objects and advantages are achieved will be more fully understood when considered in conjunction with a description of the preferred embodiments of the invention, and as shown in the drawings, in which like reference numerals represent corresponding parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a can body holder and die set constructed according to the present invention.

FIG. 2 is an exploded vertical sectional view of the die set of FIG. 1, prior to assembly thereof.

FIG. 3 is a side elevational view of the backup die member of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a can holder assembly and a die set 12. The can holder assembly comprises a generally cup shaped base member 14 having side wall portions 16 thereof, which include an opening 18 extending radially therethrough for receiving a set screw to lock a can accommodating cylinder 20 into the position shown in FIG. 1. A so-called Allen head cap screw 22 extends through the bottom of the cup shaped base member 14 for locating the same in any desired position. The phantom lines shown on the inner surfaces 24 of the cylinder illustrate the position of an unflanged beer can body having a domed-in portion at the bottom thereof which is conventional for extruded or drawn cans to add strength in bending thereto. If a conventional can is to be necked in, the screw 22 would be flush with the bottom of the base member 14.

The die set 12 is shown to comprise a holder 26 which is attached to means (not shown) for moving the same into and out of close contact with the can holder assembly 10. The die set proper comprises an outer die 28, and an inner die 30, the shank portion 32 of the inner die being located in a bore 34 which is axially aligned with the outer die 28. An Allen head cap screw 36 or like fastener is used to secure the inner and outer die members 28, 30 in the desired position in relation to each other.

Referring now to FIG. 2, it can be seen that the outer die 28 includes an inwardly tapering first inner, orienting surface 38 connected by a smooth radius to a second, short relatively vertical support surface 40, which is connected by an s-curved, shoulder-forming surface 42 which is in turn connected to a relatively straight third or neckforrning inner surface 44. A finished can body treated with such a die will have respectively inwardly and outwardly tapering radiuses defining a shoulder, above or below which will be a neck portion of reduced diameter on the can body. In the case of three-piece cans, both top and bottom portions will have reduced diameter, necked-in portions just below where the double seam joins an end to the body.

The inner or backup die 30 includes the lower shank portion 32 referred to above, a head portion 46, including a flat front surface 48, a fastener accommodating recess 50, a head radius 52 terminating in a head flange 54 which is a continuation of the radius 52. A skirt member 56 including a mating flange 58 which serves to connect the skirt 56 with the flange 54 is disposed below the head radius 52 and is attached thereto, as by a tight press fit. A stiff but resilient rubber ring 60 is disposed between the upper shank portion 62 of the inner die 30 and the inside surface of the skirt 58. A backup washer 64 is removably mounted on the bottom portion of the upper shank 62 and abuts the bottom surface 66 of the rubber ring 60.

Referring now to FIG. 3, it will be seen that the exterior of the skirt 56 contains a plurality of upwardly extending slots 68 terminating in small, circular cutouts 70, thereby dividing the lower portions of the skirt 58 into a plurality of segments 72 which are spaced apart from each other a distance equal to the width of the slots 68.

Although the reasons for the success of this die set in providing cans with reduced diameter neck portions which are free from flat spots and cracks in the area of the can body side seam are not clearly understood, it is believed that the relative flexibility of the skirt segment 72 in accommodating for the extra thicknesses of metal present in the side seam enables the can body to assume the contours of the outer dies 28 without causing flat spots and without binding in the thin neck-accommodating clearance area 74 between the skirt 72 and the inner surfaces 40, 42, 44 of the outer die 28.

It is also believed that the provision of the rubber ring 60 allows a control of the skirt 58 and the segments thereof 72 which may be accounted for by the ability of the rubber 60 to equalize the force required to form the metal throughout the entire rubber ring 60.

The provision of the backup washer 64 is optional, but its use has been found helpful in making can body necks, inasmuch as it is a means for changing the compressive forces applied to the rubber without changing the composition or density thereof while enabling a given or desired clearance to be maintained between the ring 60 and the bottom of the outer die 28.

In the use of the die set 12 for producing a uniform reduced-diameter neck portion in a two piece can body, the body may be placed in the holder unit 10, and suitable clamping means are used to force the end of the can body into the die set, cold working the top or bottom portion thereof into a reduced diameter neck or necked-in portion, connected to the vertical sidewall portion of the body by a shoulder consisting of an inwardly and upwardly extending (in the case of the top portion of the can) shoulder portion, joined respectively to the neck and the sidewall portions by two smooth curves.

FIG. 1 shows the holder 10 as surrounding the can, but it will be understood that, with a die set made according to the present invention, the lateral support which appears to be afforded by the cylinder 20 is not really necessary; it is merely necessary to place sufiicient force on the base of the can body to press the top portion into the die set 12. The final neck is formed when the top portion of the body is forced fully into the working clearance area 74.

A second method of the present invention involves performing the same steps with the body of a three-piece style can, except that the screw 22 is placed flush with or below the level of the bottom of the base member 14. In such a case, the operation can be performed either with a can end on or off the can body.

A third method, and one which is preferred for use with the die set of the present invention, comprises resting or supporting a can body on any suitable means well known in the can industry, such as magnetically holding the body in position on a star wheel comprising two flanges disposed parallel to each other and having cutouts thereon of a contour complementary to that of a can body. Such can holders are known, for example, to be used on so-called 360 body sprayers. When the body is supported as thus described, two identical die sets such as the set shown at 12 are moved simultaneously into position over both ends of the can body. Any means for moving the die sets can be used, such motions being well known in the can industry, and being used, for example, on can body testers or the like.

In all the cases described above, the neck portion is readily formed in the top and bottom portions of the can body, and, even in the case of a three piece can body, that is, one in which multiple thicknesses of metal are present at a side seam of the body, the neck and the shoulder forming the neck are of smooth and uniform contour, even though it is not necessary in making either the inner or outer dies to provide extra clearance for such additional thicknesses of metal. Likewise, the die set of the present invention works equally well when used with can bodies which do not have side seams, and thus may be used interchangeably in manufacture without the necessity for changing to different die sets for accommodating different styles of bodies.

Although the skirt portion 56 containing the segments 72 is shown as being separate from the head portion 46 of the inner die 30 containing the flange 54, and althrough such construction is preferred in order to increase the flexibility of the skirt portion 56 under stress, it will be understood that the skirt 56 and the head portion 46 may be formed integrally, provided that slots 68 are included for dividing the skirt portion 56 of the die set into segments 72.

Where the skirt 56 and the head 46 are formed separately and joined together in use, the two are sized so that the skirt 56 may be pressed in place with the mating flange portion 58 thereof locked just inside the flange 54 with a tight press fit, so that these parts are firmly held together, although no separate or additional fastening means need be used. This allows maximum flexibility of the skirt in use, but the combination of the tight press fit and the location of the inner die 30- relative to the outer die 28 assures that the skirt 56 remains in place during use of the die set.

Likewise, it will be understood that, as used herein, and in the appended claims, directionor orientation-indicating words such as upper, lower, horizontal, top, bottom, etc., shall mean the parts as shown in the drawings hereof, since it is well known that these parts and elements may be placed in any position in use without affecting their character or essential function.

It can thus be seen, from the above description, and from the appended claims, taken in conjunction with the drawings, that the present invention provides a new and useful die set unit and method for can manufacture having a number of novel advantages and characteristics, including those hereinbefore pointed out and others which are inherent therein. I contemplate that certain changes and variations may be made by those skilled in the art without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. A die set for use in forming a reduced diameter neck portion of a can body, said die set comprising, in combination, an outer, neck forming die having principal body portion with a central cavity therein, said central cavity including a first, slightly inwardly tapering orienting surface, a second, relatively short vertical can body side wall engaging surface portion, a third, inwardly tapering, shoulder forming surface, and a fourth, generally vertical, reduced diameter neck forming surface, each of said surfaces being connected to the surfaces immediately adjoining it by a smooth curve, and an inner, backup die, including a head portion having a generally horizontal front face portion and a generally vertically extending flange portion, a segmented skirt portion depending from said flange portion and extending vertically downwardly therefrom, said inner and outer die members being sized so that when said inner member is in place in relation to said outer member, the lower portion of said skirt member is separated from said neck forming surface by a distance substantially equal to one thickness of the body wall of a can placed between said surfaces.

2. A die set as defined in claim 1 in which there is further included a stiff but resilient, hard, rubbery ring member disposed inside said skirt portion of said inner die, and in contact with said skirt member throughout substantially the entire inner peripheral surface of said skirt member.

3. A die set as defined in claim 1 in which said skirt portion is removably attached to said flange portion of said head portion.

4. A die set as defined in claim 1 in which said segmented skirt portion is comprised of a plurality of individual segments separated from each other by a plurality of vertically extending slots, each being less than oneeighth of an inch wide.

5. A die set as defined in claim 2 in which a metal backup ring is disposed between the bottom surface of said rubber ring member and the inner horizontal surface of said outer die member.

6. A method of forming a reduced diameter neck portion in a can body, comprising the steps of providing inner and outer die members, wherein said outer member includes a plurality of inwardly facing surfaces, including an orienting surface, a shoulder forming surface, and a neck forming surface, each of three said surfaces being of smaller diameter than the preceding surface, providing a backup die having a rigid downwardly extending flange and a downwardly extending skirt portion, said skirt portion including a plurality of individual segments separated from each other by narrow slots, and providing a stiff but resilient rubber ring member disposed snugly inside said skirt member and providing resistance to inward movement thereof, and of moving one cylindrical edge portion of a can body into said die set, thereby imparting a reduced diameter end portion thereto, said neck portion being connected to said body wall portion by a smooth shoulder portion.

References Cited UNITED STATES PATENTS 1,370,5'56 3/ 1921 Phelps 72-465 2,013,654 9/ 1935 Hothersall. 3,196,819 7/1965 Lechner et al ll3-l20 3,225,581 12/ 1965 Hinderer 7237O RICHARD J. HERBST, Primary Examiner US. Cl. X.R.

72-466; ll3-l, 

